Electrolytic process of producing diacetone-keto-gulonic acid



Patented July 3, 1951 ELECTROLYTIC PROCESS OF PRODUCING DIACETONE-KETO-GULONIC ACID Albert Verheyden, St. Denijs-Westrem, Belgium No Drawing. Application August 13, 1946, Serial No. 690,337. In Belgium September 22, 1945 4 Claims. (01. 204-79) This invention rel-ates to the production of diacetone-keto-gulonic acid and it has for its object to prepare same by electro-chemical oxidation of sorbose diacetone in alkaline solution by the direct process i. e. in the absence of any oxygen carrier.

The oxidation processes of organic compounds by the electro-chemical method are far less numerous than the reduction processes. It is generally admitted that the action of the anodic oxygen is too violent and too difiicult to keep at a suitable energetic level.

Only a small number of cases of electrochemical oxidation of alcohols or aldehydes in alkaline solution by the direct process are known and publications available in Belgium do not disclose any case of direct electro-chemical oxidation of a hexose or of a combination of a hexose with acetone, cyclohexanone, formaldehyde or other compounds capable of protecting the hydroxyl groups of the hexose. Thus, diacetoneketo-gulonic acid has been obtained hitherto by chemical oxidation of sorbose diacetone, chiefly by means of potassium permanganate.

In accordance with the present invention, the direct electro chemical oxidation of sorbose diacetone into diacetone-keto-gulonic acid is obtained by carrying out electrolysis with an anode having in normal alkaline solution an overvoltage of 0.57 to 0.67 volt. It has been found that the energetic level of the oxygen produced by such limited overvoltage is favorabl to the formation of diacetone-keto-gulonic acid and that by also observing certain precautions in order to reduce the effect of cathodic reduction, oxidation yields of 70 to 85% are obtained.

The anodic overvoltage depends on various factors, first among these being the nature of the metal used and the current density, but other factors of less importance may also intervene, such as the nature of the surface of the metal, so that it is not possible by merely theoretical deduction to determine the most favorable metals and the permissible current densities.

It has been found that anodes of copper, nickel, silver or their alloys may be used. The suitable current density may vary considerably from one to another metal. Satisfactory results are usually obtained with anodic current densities comprised between 0.1 and a. per square decimeter.

It is also advisable to limit the effect of cathodic reduction either by the use of a diaphragm, or by selecting a proportion between the oathodic current density and the anodic current density comprised between 2 and 20. Furthermore it.

ing the cathode. As such, iron, copper, nickel and their alloys may be taken into consideration.

The process according to the invention is characterised by its simplicity, its easy performance on an industrial scale, its economy for a given output and the possibility of operating in solutions of much higher concentration than with the usual chemical process.

Examples 1. A solution containing 8% sorbose diacetone, 5% KOI-I, and 2% K2Cr04 is subjected to electr-olysis between copper electrodes, with an anode density of 3.5 a./dm. The temperature is kept at 15 C. and the electrolyte is preferably stirred. After the electrolysis, the diacetone-keto-gulom'c acid is isolated by concentration and precipitation,

2. A solution containing 8% sorbose diacetone, 5% KOH and 2% K2CrO4 is subjected to electrolysis between nickel electrodes and with an anode density of 7.5 a./dm. and a cathode density of 30 a./dm. The temperature is kept at 10 C. After the electrolysis the separation of the diacetone-keto-gulonic acid formed from the sorbose diacetone is carried out according to known methods.

3. A solution as in Example 2 is subjected to electrolysis between a silver anode and an iron cathode, with an anode density of 8.4 a./dm. at 5 C, The operation is completed as in Example 2.

4. A solution of 4% sorbose diacetone, 5% KOH and 2% K2CIO4 is subjected to electrolysis with a Monel anode and an anode density of 2.9 a./dm. The operation is completed as in Example 2.

I claim:

1. In a process of producing diacetone-ketogulonic acid, the step comprising subjecting sorbose diacetone in an aqueous alkaline solution to anodic oxidation employing an anodic current density between 0.1 and 10 amps. per square decimeter, the proportion between the cathodic current density and the anodic current density beingmaintained between 2:1 and 20:1, and an anode having in one normal alkaline solution an overvoltage between 0.57 and 0.6? volt, said anodic oxidation being effected in the absence of heat supplied from an external source and in the absence of any oxygen carrier effective in an alkaline medium to oxidize said sorbose diacetone.

2. The process of claim 1 wherein the anode consists of copper.

3. The process of claim 1 wherein the anode consists of nickel.

4. The process of claim 1 wherein the anode consists of silver.

ALBERT VERHEYDEN.

REFERENCES CITED The following references are of record in the file of this patent:

4 UNITED STATES PATENTS Number Name Date 2,084,641 Haller June 22, 1937 2,301,811 Reichstein Nov. 10, 1942 2,367,251 Weijlard et a1 Jan. 16, 1945 FOREIGN PATENTS Number Country Date 1,624 Great Britain Nov. 23, 1895 OTHER REFERENCES G1asstone et a1.: Electrolytic Oxidation and Reduction, (1936), pp. 62-64, 339-341.

Chemical Abstracts, vol. 40 (1946), p. 5447 (U.

15 S. S. R. patent, 64,479, April 30, 1945). 

1. IN A PROCESS OF PRODUCING DIACETONE-KETOGULONIC ACID, THE STEP COMPRISING SUBJECTING SORBOSE DIACETONE IN AN AQUEOUS ALKALINE SOLUTION TO ANODIC OXIDATION EMPLOYING AN ANODIC CURRENT DENSITY BETWEEN 0.1 AND 10 AMPS. PER SQUARE DECIMETER, THE PROPORTION BETWEEN THE CATHODIC CURRENT DENSITY AND THE ANODIC CURRENT DENSITY BEING MAINTAINED BETWEEN 2:1 AND 20:1, AND AN ANODE HAVING IN ONE NORMAL ALKALINE SOLUTION AN OVERVOLTAGE BETWEEN 0.57 AND 0.67 VOLT, SAID ANODIC OXIDATION BEING EFFECTED IN THE ABSENCE OF HEAT SUPPLIED FROM AN EXTERNAL SOURCE AND IN THE ABSENCE OF ANY OXYGEN CARRIER EFFECTIVE IN AN ALKALINE MEDIUM TO OXIDIZE SAID SORBOSE DIACETONE. 